JP2007242611A - Method of depositing nanoparticle coating on bipolar plate and removing nanoparticle coating from land of bipolar plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bipolar plate used for a fuel cell, and excelling in durability. <P>SOLUTION: This method includes a process comprising: submerging a fuel cell bipolar plate in a bath comprising nanoparticles and a liquid phase comprising a nanoparticle dispersion agent, wherein the bipolar plate includes an upper surface having a plurality of lands and channels; removing the fuel cell bipolar plate from the bath so that a coating comprising nanoparticles adheres to the fuel cell bipolar plate; thereafter, while the coating is wet and before the coating is dried and solidified, removing the coating comprising nanoparticles from the lands of the bipolar plate, leaving coating comprising nanoparticles in the channels; and drying the coating in the channels. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Application No. 60 / 776,363 filed on Feb. 24, 2006.

TECHNICAL FIELD The present invention relates to a method of coating a fuel cell element.

  US Pat. No. 6,025,057 to Angelopoulos et al. Discloses a solution to problems in the manufacture of electronic packages, such as printed circuit boards. The specification discloses that the key required for printed circuit board manufacture is to achieve proper Pd / Sn seed layer catalyst loading. Insufficient Pd catalyst will create gaps in the copper growth circuit layer, resulting in an open circuit. Too much catalyst can cause both poor adhesion and lateral conduction. Adhesion failure can cause electroless plating solution to leak under the photoresist and deposit copper between circuit elements, causing a short circuit (circuit short). A solution to the disclosed problem involves depositing an organic polyelectrolyte on an organic substrate such as a circuit substrate formed from glass fibers and epoxy. A colloidal palladium-tin seed layer is deposited on top of the organic polyelectrolyte. A photoimageable polymer is then deposited on top of the seed layer, and the photoimageable polymer is patterned by photolithography to expose a portion of the seed layer. Copper is deposited on the exposed portion of the seed layer using electroless growth of copper. The organic polyelectrolyte is deposited from an aqueous solution at a pH appropriate for the desired seed catalyst coating. An example of an organic polyelectrolyte disclosed is a copolymer of acrylamide and beta-methacryloxyethyltrimethylammonium methyl sulfate. The polyelectrolyte contains a hydrolyzed amide group and is deposited on an organic substrate in an aqueous solution containing sulfuric acid having a pH of less than 4. In another disclosed embodiment, the polyelectrolyte is deposited on an organic substrate in an aqueous solution containing sodium hydroxide at a pH greater than 10. Another disclosed polyelectrolyte is a cationic polyamide-amine. A neutral aqueous solution is developed with a polyelectrolyte in a concentration range of 0.2 to 1.2 g / L. A seed layer of Pd / Sn colloidal suspension is deposited on the polyelectrolyte.

Angelopoulos et al., US Pat. No. 5,997,997, issued December 7, 1999, is a printed circuit board that often suffers from excessive seed deposition in conventional electroless plating processes. A solution to the problems associated with manufacturing circuit structures is disclosed. Excess seed on the circuit board causes a leakage short, and the adhesion of the photoresist used to circuitize the circuit board on the seed layer becomes poor due to the non-uniform surface. Excess seed layer can also cause unwanted metal plating in subsequent processing steps. The disclosed solution includes providing a workpiece that includes a substrate coated with a polymeric dielectric layer. The workpiece having the polymeric dielectric layer is then fired in the ambient atmosphere. The workpiece is then treated with a polymeric surfactant that can hydrogen bond to weak acid groups on the surface of the polymeric dielectric. The disclosed polymeric surfactants are cationic polyelectrolytes having amide groups, such as cationic polyacrylamides or cationic polyamide-amines. The polymeric surfactant has a molecular weight in the range of 10 ⁵ to 10 ⁷ . The disclosed polyelectrolytes are described in Polytech, Inc. Available under the trade name “Polytech”.

  In areas not related to printed circuit boards, the manufacture of fuel cell stacks involves the creation of bipolar plates with water management features. The instability caused by liquid film capillary action in hydrophobic bipolar channel causes liquid stagnation and loss of fuel cell performance. Plasma treatment to introduce hydrophilic functional groups onto the surface of the bipolar plate has been shown to eliminate liquid stagnation and improve fuel cell performance. However, such plasma processing techniques are very expensive and time consuming. Therefore, an alternative processing method is needed. One such option is disclosed in assignee's US Provisional Patent Application No. 60 / 707,705, entitled “Fuel Cell component With Coating Including Nanoparticles”. There is disclosed an embodiment that involves spraying a thin coating of hydrophilic nanoparticles onto the surface of a bipolar plate. However, Applicants have found some concerns regarding durability under certain conditions. (1) the lack of color reflection from the coating suggests that the coating is not coherent, (2) organic acids and surfactant residues remain in the coating, and (3) It includes that the strength of the coating is a result of agglomeration rather than a result of adhesive interactions (ie, there is little or no chemical bonding of the coating to the substrate).

  The present invention provides an alternative to the prior art.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION In one aspect of the invention, a fuel cell bipolar plate comprising a top surface having a number of lands and channels formed therein, a nanoparticle, and a liquid phase comprising a nanoparticle dispersant. The fuel cell bipolar plate is removed from the bath so that the coating comprising the nanoparticles adheres to the fuel cell bipolar plate before the coating is dried and solidified while the coating is wet. Removing, removing the coating comprising the nanoparticles from the land of the bipolar plate, leaving the coating comprising the nanoparticles in the channel, and drying the coating.

  Other aspects of the invention will become apparent from the detailed description set forth below. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The following description of the embodiments is exemplary in nature and is not intended to limit the invention and its application or uses.

  One aspect of the present invention includes a method comprising applying an aqueous solution comprising a polyelectrolyte polymer to a fuel cell element. The polyelectrolyte polymer may contain a cationic functional group and / or an anionic functional group. Examples of suitable cationic polyelectrolyte polymers include, but are not limited to: copolymers of acrylamide and quaternary ammonium salts; polyamide-amines; polyallylamine hydrochlorides; epoxy azopolymers; and acrylic acid Azopolymer. Examples of suitable fuel cell elements include, but are not limited to, bipolar plates, diffusion media, and membrane electrode assemblies. The second coating material may be applied to the polyelectrolyte polymer adhered to the fuel cell element. By way of example, the second coating material includes, but is not limited to, a hydrophilic or hydrophobic material. In one embodiment, the second coating material may include nanoparticles. Suitable second coating materials are disclosed in assignee's US Provisional Patent Application No. 60 / 707,705, entitled “Fuel Cell component With Coating Including Nanoparticles,” the disclosure of which is herein incorporated by reference. Incorporated into. In one aspect of the present invention, the second coating material includes a hydrophilic material comprising negatively charged groups capable of forming strong ionic bonds with the cationic polymer (polyelectrolyte) coated on the fuel cell element. .

  FIG. 1 is a process flow graph illustrating a process according to an aspect of the present invention. In this embodiment, the first step 100 of the process includes applying an aqueous polyelectrolyte polymer solution to a fuel cell element such as a bipolar plate. The second step 102 of the process includes removing unadhered polyelectrolyte polymer from the fuel cell element, for example by rinsing the fuel cell element in deionized water. The third step 104 of the process includes applying a second coating material to the polyelectrolyte polymer adhered to the fuel cell element. The second coating material may be, for example, a material containing nanoparticles.

  The fourth step 106 of the process includes removing the second coating material not adhered to the polyelectrolyte polymer, for example by rinsing the fuel cell plate in deionized water. The first to fourth steps (100 to 106) may be repeated a plurality of times to form a plurality of layers of the polyelectrolyte polymer and the second coating material adhered thereto.

  In one aspect of the invention, the fuel cell element is a bipolar plate including a gas flow field defined by a number of lands and channels formed on the top surface of the bipolar plate. The fifth step 107 of the process involves removing the coating material from the bipolar plate lands while the coating is still wet, dried and solidified. The coating is left in the bipolar plate channel. In one aspect of the present invention, a coating comprising nanoparticles while the coating is wet, even if a polyelectrolyte coating is applied to the bipolar plate to enhance the adhesion of the nanoparticle coating to the bipolar plate. Is found to be easily removed from the bipolar plate.

  FIG. 2 is a process flow diagram illustrating a process according to another aspect of the invention. The first step 108 of the process includes removing grease and / or contaminants from the bipolar plate by immersing the fuel cell bipolar plate in a pretreatment solution at, for example, 65 ° C. for 3 minutes. One embodiment of the pretreatment solution includes a K2-grade (FDA microelectronics grade) degrease agent. The second step 110 of the process includes rinsing the bipolar plate in a first bath of deionized water, for example at 57 ° C. for 1 minute. The third step 112 of the process involves rinsing and cleaning the bipolar plate in a second bath of deionized water, for example at 57 ° C. for 1 minute. The fourth step 114 of the process includes immersing the bipolar plate, for example, for about 2 minutes in the first aqueous solution containing the first polyelectrolyte polymer. In one aspect of the invention, the first polyelectrolyte polymer is a cationic polyacrylamide, such as Superfloc C-442 or C-446 available from CYTEC. Another example of a cationic polyacrylamide polymer is Polytech, Inc. Polytech 7M available from The fifth step 116 of the process includes rinsing the bipolar plate in a third bath of deionized water, for example, at 57 ° C. for 1 minute to remove unadhered first polyelectrolyte polymer. The sixth step 118 of the process includes rinsing and cleaning the bipolar plate in a fourth tank of deionized water, for example at 57 ° C. for 1 minute. The seventh step 120 of the process includes immersing the bipolar plate in a second aqueous solution containing the second coating material at, for example, 57 ° C. for 1 minute. The second coating material can include hydrophilic nanoparticles, such as X-Tec 4014 or 3408 available from Nano-X. The eighth step 122 of the process includes rinsing the bipolar plate in a fifth tank of deionized water, for example, at 57 ° C. for 1 minute, and unbonded second coating material not adhered to the first polyelectrolyte polymer. Is included. The ninth step 124 of the process involves rinsing and cleaning the bipolar plate in a sixth tank of deionized water, for example at 57 ° C. for 1 minute. In the tenth step 126 of this process, the fourth to ninth steps (114 to 124) are repeated three times in total to form a plurality of layers of the polyelectrolyte polymer and the second coating material thereon. Is included. The eleventh step 127 of the process involves removing the coating material from the bipolar plate lands before the coating is still wet and dried and solidified. The coating is left in the bipolar plate channel. Thereafter, the twelfth step 128 of the process includes drying the bipolar plate, for example, by placing the bipolar plate on a drying shelf for 10-15 minutes.

  A suitable example of a second coating material comprising nanoparticles is disclosed in commonly assigned US Patent Application No. 60 / 707,705. Examples of such second coating materials are described below. One aspect of the invention includes a fuel cell element having a substrate, such as a bipolar plate, having a polyelectrolyte polymer thereon and a second coating material comprising nanoparticles on the polyelectrolyte polymer. However, it is not limited to this. The nanoparticles may have a size of about 2 to about 100 nm, preferably about 2 to about 20 nm, and most preferably about 2 to about 5 nm. Nanoparticles can include inorganic and / or organic materials. The second coating material can include compounds containing hydroxyl groups, halide groups, carboxyl groups, ketone groups, and / or aldehyde groups. The second coating material can make the fuel cell element, such as a bipolar plate, hydrophilic.

  In one aspect of the present invention, a fuel having a permanent hydrophilic coating comprising a polyelectrolyte polymer thereon and nanoparticles having hydrophilic side chains on the polyelectrolyte polymer. A battery element is included.

  One embodiment of the present invention includes nanoparticles comprising 10 to 90% by weight of inorganic structure, 5 to 70% by weight of hydrophilic side chains, and organic side chains having 0 to 50% by weight of functional groups. A permanent hydrophilic coating is included. In one embodiment of the present invention, the hydrophilic side chain is an amino group, sulfonate group, sulfate group, sulfite group, sulfonamide group, sulfoxide group, carboxylate group, polyol group, polyether group, phosphate group, or phosphonate group. It is.

  In one embodiment of the present invention, the second coating material may include an organic side chain, and the functional group of such an organic side chain includes an epoxy group, an acryloxy group, a methacryloxy group, a glycidyloxy group, an allyl group, a vinyl group, A carboxyl group, a mercapto group, a hydroxyl group, an amide group or an amino group, an isocyano group, a hydroxy group, or a silanol group. In one aspect of the invention, the coating has a pH of 3-10.

  Another aspect of the present invention includes depositing a slurry solution comprising nanoparticles and a vehicle on the polyelectrolyte polymer on the fuel cell element and then removing the medium. The medium includes water, alcohol, and / or other suitable solvents. In one embodiment, the media comprises 4-5% by weight nanoparticles and the remaining media portion. In one aspect, the media can be removed at a temperature of about 80 to about 180 ° C. The treatment time can range from 10 minutes at 80 ° C. to 10 seconds at 180 ° C.

  Suitable slurry materials are available from Nano-X Gmbh under the trademarks HP 3408 and HP 4014. The slurry material can provide a permanent hydrophilic coating that allows the fuel cell operating conditions to last longer than 2500 hours. This permanent coating can be formed on metals such as aluminum and high-grade stainless steel, polymer substrates, and conductive composite substrates such as bipolar plates.

  US Patent Application No. 2004/0237833, incorporated herein by reference, describes a number of methods for preparing slurries useful in the present invention, which are described below.

Example 1
221.29 g (1 mol) of 3-aminopropyltriethoxysilane is added to 444.57 g of sulfosuccinic acid with stirring and heated to 120 ° C. in a silicon bath for 5 hours. After the reaction mixture has cooled, 20 g of viscous fluid is mixed with 80 g (0.38 mol) tetraethoxysilane and absorbed into 100 g ethyl alcohol. This solution is then mixed with 13.68 g (0.76 mol) of 0.1N HCl solution and placed in a water bath at 40 ° C. overnight. This yields approximately 2 nm hydrophilic nanoparticles with reactive end groups. The resulting solution was diluted with a mixture of water 1/3 and N-methylpyrrolidone (NMP) 2/3 to a solid content of 5% and applied on a glass plate by spraying to a wet film thickness of 10-20 μm. To do. Subsequently, the substrate is densified at 150 ° C. for 3 hours in a circulating air drying cabinet.

Example 2
221.29 g (1 mol) of 3-aminopropyltriethoxysilane is added to 444.57 g of sulfosuccinic acid with stirring. The solution is then heated to 130 ° C. in a silicon bath. After a reaction time of 1 hour, 332.93 g of an alkaline stabilized silica gel solution of Levasil 300/30% type (pH 10) are added to the reaction solution with stirring. After a reaction time of 12 hours, the mixture is diluted with water to a solids content of 5%. This gives hydrophilic nanoparticles of about 15 nm with reactive end groups. This system is applied to the plasma activated polycarbonate sheet by dipping and subsequently dried in a circulating air drying cabinet at 130 ° C. for 5 hours.

Example 3
123.68 g (0.5 mol) of 3-isocyanatopropyltriethoxysilane was added to 600 g (1 mol) of polyethylene glycol 600 and 0.12 g of tin dibutyllaurate (0.1 wt. For 3-isocyanatopropyltriethoxysilane). %) And then heated to 130 ° C. in a silicon bath. 25 g (0.12 mol) of tetraethoxysilane and 33.4 g (0.12 mol) of 3-glycidyloxypropyltriethoxysilane are added to 50 g of the resulting solution (solution A) with stirring. After adding 15.12 g (0.84 mol) of 0.1N HCl solution, the mixture is hydrolyzed and concentrated at room temperature over 24 hours. This gives hydrophilic nanoparticles of about 5 nm with reactive end groups.

Example 4
12.5 g (0.05 mol) of 3-methacryloxypropyltriethoxysilane, 12.5 g of 20% CeO ₂ aqueous solution (from Aldrich) and 50 g of ethyl alcohol were mixed with 50 g of the solution A described in Example 3 In order to make the water uniform, it is added with stirring, and hydrophilization is carried out over 48 hours. After adding 0.375 g of Ingacure 184 (3 wt% for 3-methacryloxypropyltrimethoxysilane) from Ciba Spezialitaten Chemie, the mixture was heated to a polycarbonate film (flamed) with a wet film thickness of up to 30 μm. coating sheet) by spraying and first dried by heat in a circulating air drying cabinet at 130 ° C. for 10 minutes. Thereafter, to photochemically dried using Hg emitters having a radiation output 1~2J / cm ^2.

  The scope of the present invention is not limited to the second coating material described above and the method of manufacturing the same, but includes other second coating materials including nanoparticles formed on the polyelectrolyte polymer on the fuel cell element. The following is a description of further aspects of the second coating material and method of making the same.

For example, suitable nanoparticles, SiO _{2 and, HfO 2, ZrO 2, Al} 2 O 3, SnO 2, Ta 2 O 5, Nb 2 O 5, MoO 2, IrO 2, of RuO ₂ other like Metal oxides, metastable oxynitrides, nonstoichiometric metal oxides, oxynitrides, and derivatives thereof containing carbon chains or containing carbon, and mixtures thereof, Is included, but is not limited to these.

  In one embodiment, the second coating material is hydrophilic and includes at least one Si-O group, at least one polar group, and at least one group comprising a saturated or unsaturated carbon chain. In one embodiment of the present invention, the polar group can include a hydroxyl group, a halide group, a carboxyl group, a ketone group, or an aldehyde group. In one embodiment of the invention, the carbon chain may be saturated or unsaturated and may have 1 to 4 carbon atoms. The second coating material includes, for example, Au, Ag, Ru, Rh, Pd, Re, Os, Ir, Pt, rare earth metals, alloys thereof, polymeric carbon, or graphite to improve conductivity. An element or a compound may be included.

  In one embodiment of the invention, the second coating material comprises Si—O groups and Si—R groups, R comprises saturated or unsaturated carbon chains, and the molar ratio of Si—R groups to Si—O groups is 1 / It is 8 to 1/2, preferably 1/4 to 1/2. In another aspect of the invention, the second coating material further comprises hydroxyl groups to improve the hydrophilicity of the coating.

Another aspect of the present invention is a fuel cell element having an element having a polyelectrolyte polymer thereon and a second coating material on the polyelectrolyte polymer, wherein the coating is derived from siloxane. Is included. Siloxanes may be linear, branched or cyclic. In one embodiment, the siloxane has the formula R ₂ SiO, where R is an alkyl group.

  In another aspect of the invention, the second coating material is of the formula

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are each H, O, Cl, or a saturated or unsaturated carbon chain having 1 to 4 carbon atoms. Often, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ can be the same or different.

  In another aspect of the invention, the second coating material is of the formula

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are each H, O, Cl, or a saturated or unsaturated carbon chain having 1 to 4 carbon atoms. Often, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ may be the same or different, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ At least one of which is a carbon chain having at least one carbon atom).

  Another aspect of the invention is a fuel cell element having a polyelectrolyte polymer thereon and a second coating material on the polyelectrolyte polymer, wherein the second coating material is 1-100 nm, preferably Includes nanoparticles having a size of 1-50 nm, most preferably 1-10 nm, wherein the nanoparticles include elements comprising silicon, saturated or unsaturated carbon chains, and polar groups. In one embodiment, the second coating has an average thickness of 80-100 nm.

  As shown in FIG. 3, the fuel cell element includes a relatively thin substrate 12 that is embossed to define a gas flow field (gas flows therethrough) defined by a plurality of lands 16 and channels 14. It may be a bipolar plate. An aqueous solution containing the polyelectrolyte polymer may be deposited on the top surface 18 of the bipolar plate so that at least a portion of the polyelectrolyte polymer adheres to the substrate 12 to form the first layer 20. The aqueous solution containing the polyelectrolyte polymer can be deposited on the upper surface 18 before or after the substrate 12 is embossed. Thereafter, an aqueous solution containing the second coating material may be applied to the first layer 20 of polyelectrolyte polymer and dried to form the second coating material 22 on the first layer 20 of polyelectrolyte polymer. . The substrate 12 may be a metal such as stainless steel.

  With reference to FIG. 4, another aspect of the present invention includes a substrate 12 machined to define a gas flow field defined by a plurality of lands 16 and channels 14 through which gas flows. A fuel cell bipolar plate 10 is included. An aqueous solution containing the polyelectrolyte polymer can be deposited on the top surface 18 of the bipolar plate such that at least a portion of the polyelectrolyte polymer adheres to the substrate 12 to form the first layer 20. Thereafter, an aqueous solution containing the second coating material may be applied to the first layer 20 of the polyelectrolyte polymer and dried to form the second coating material 22 on the first layer 20 of the polyelectrolyte polymer. Good. The substrate 12 may be a metal such as stainless steel.

  With reference to FIG. 5, in one embodiment, the substrate 12 may be coated with a first layer 20 of polyelectrolyte polymer, and a mask material 24 may be selectively deposited on the first layer 20. Thereafter, a second coating material 22 may be deposited over the first layer 20 and the mask material 24. As shown in FIG. 6, the mask material 24 and the second coating material directly above the mask material 24 are removed, leaving a portion of the second coating material 22 selectively on the first layer 20. Also good. The substrate 12 can be embossed to leave the second coating material in the channel 14 of the gas flow field. The aqueous solution containing the polyelectrolyte polymer and the aqueous solution containing the second coating material may be applied or deposited on the substrate 12 by dipping, spraying, rolls, brushes, or the like.

  With reference to FIG. 7, in another aspect, mask material 24 may be selectively deposited on top surface 18 of substrate 12. The first layer 20 of polyelectrolyte polymer may be formed on the mask material 24 and the unmasked portion of the top surface of the substrate 12. A second coating material may then be formed on the first layer 20. Thereafter, the mask material 24 and a portion of the first layer 20 and the second coating material 22 directly above the mask material 24 are removed to provide an exposed portion 18 'on the top surface of the substrate 12 as shown in FIG. You may leave. Similar masking techniques can be used on the machined substrate.

  In another aspect of the present invention, the coating method may or may not use the coating method using an aqueous solution containing a polyelectrolyte. In this aspect of the invention, the fuel cell element is submerged in a bath containing the nanoparticles described above and a liquid phase comprising at least 30% by volume of the nanoparticle dispersant of the liquid phase. The liquid phase may comprise 30-100% by volume or any volume% nanoparticle dispersant in between. The liquid phase may contain 0.1-70% by volume of the liquid phase or any volume% water therebetween. Suitable nanoparticle dispersants include, but are not limited to, alcohols including at least one of methanol, ethanol, or propanol. Organic solvents that can form a solution with water and impart dispersibility properties are considered suitable dispersants. When using X-Tec 3408 or 4014, the nanoparticles are composed of 4-5% by weight of X-tec material. In one embodiment of the invention, the nanoparticles are present in an amount of 0.2-5% by weight of the bath solution.

  After the fuel cell element is submerged in the tank and removed from the tank, the fuel cell element is optionally rinsed with water (eg, DI water) to remove any coating not adhered to the fuel cell element, and then the ambient air, convection oven, The fuel cell element may be exposed to at least one of infrared energy or microwave energy and dried. Submerging, rinsing and drying yields a nanoparticle coating having a thickness of at least 25 nm. In one aspect of the invention, a nanoparticle coating having 0.4 atomic weight silicon in the coating is obtained on the fuel cell element by submerging, rinsing and drying.

  Thereafter, the submerging, rinsing, and drying steps may be repeated multiple times to produce multiple layers of nanoparticle coatings on the fuel cell element. For example, the submerging, rinsing, and drying steps can be performed on at least the same fuel cell element to obtain a nanoparticle coating that is at least 100 nm thick. In one aspect of the present invention, the submerging, rinsing, and drying steps are repeated to obtain a nanoparticle coating having 1.5 atomic weight silicon in the coating on the fuel cell element. Suitable materials for the nanoparticles are as described above, in particular X-Tec 3408 or 4014 available from Nano-X or silica nanopowder available from Sigma-Aldrich. One embodiment of the present invention includes at least 1 part by volume of X-Tec 3408 or 4014 per 19 parts by volume of solvent, which is at least 30% by volume alcohol water.

  Referring to FIG. 9, one aspect of the present invention includes a fuel cell element 10, such as a bipolar plate, that includes a substrate 12 having a gas flow field defined by a plurality of lands 16 and channels 14. A first layer 20 of polyelectrolyte polymer is on the top surface 18 of the substrate. The first layer 20 includes a plurality of layers 19 and 21, each including a polyelectrolyte polymer formed according to the aqueous coating method described above. A second layer 22 of nanoparticles is applied on the first layer 20 of polyelectrolyte polymer. The second layer of nanoparticles 22 may be formed from a plurality of layers 200, 202, 204, 206, each comprising nanoparticles formed by the immersion method described above for depositing a continuous layer of nanoparticles. In one aspect of the invention, layers 200, 202, 204, 206 are both at least 100 nm thick and have at least 1.5 atomic weight silicon.

  Referring to FIG. 10, in one aspect of the present invention, the fuel cell element is a bipolar plate 12 having a gas flow field formed on a top surface and defined by a plurality of lands 16 and channels 14. A polyelectrolyte coating 20 and a nanoparticle coating 22 are deposited on lands 16 and channels 14, respectively, as described above. The coatings 20,22 on the lands 16 are removed leaving the coatings 20,22 in the channel 14 while the coatings 20,22 from the rinse bath are still wet and not dried and solidified. The coating above land 16 can be removed by wiping, scraping, rubbing, or light mechanical rubbing of coatings 20,22. In one embodiment of the invention, the blade 300 is moved across the land 16 to wipe the coatings 20, 22 from the land 16. The blade 300 can be formed of metal, polymer (eg, plastic), elastic material (eg, rubber), or composite material. In one embodiment of the present invention, the blade 300 is a rubber squeegee. In another aspect of the invention, the coatings 20, 22 can be removed from the lands 16 by moving a cloth or elastic material over the lands 16.

The description of the present invention is intended to be exemplary in nature and thus variations that do not depart from the spirit of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the present invention.

FIG. 1 is a process flowchart illustrating a process according to an aspect of the present invention. FIG. 2 is a process flow diagram illustrating another process according to another aspect of the present invention. FIG. 3 illustrates a fuel cell element according to one embodiment of the present invention having a first layer of polyelectrolyte polymer and a second coating material thereon. FIG. 4 illustrates a fuel cell element according to another aspect of the present invention having a first layer of polyelectrolyte polymer and a second coating material thereon. FIG. 5 illustrates a process according to one aspect of the present invention. FIG. 6 illustrates a process according to another aspect of the present invention. FIG. 7 illustrates a process according to another aspect of the invention. FIG. 8 illustrates a process according to another aspect of the invention. FIG. 9 illustrates a product according to one aspect of the present invention. FIG. 10 illustrates a process according to one aspect of the present invention.

Claims (31)

Submerging a fuel cell bipolar plate comprising a top surface having a plurality of lands and channels formed therein in a bath comprising nanoparticles and a liquid phase comprising a nanoparticle dispersant;
Removing the fuel cell bipolar plate from the vessel and adhering a coating comprising nanoparticles to the fuel cell bipolar plate;
Removing the nanoparticle-containing coating from the bipolar plate lands while leaving the nanoparticle-containing coating in the bipolar plate channel before the coating dries and solidifies while the coating is wet; and coating in the channel The method including the process of drying. The method of claim 1, wherein removing the coating from the land comprises wiping the coating from the land. The method of claim 2, wherein the wiping comprises moving the blade across the land. The method of claim 3, wherein the blade comprises a metal. The method of claim 3, wherein the blade comprises an elastic material. 4. The method of claim 3, wherein the blade comprises rubber. The method of claim 3, wherein the blade comprises a composite material. The method of claim 2, wherein the wiping includes moving a squeegee across the land. The method of claim 2, wherein the wiping comprises moving the fabric across the land. The method of claim 2, wherein the wiping comprises moving an elastic material across the land. The method of claim 1, further comprising rinsing the fuel cell element to remove nanoparticles that are not sufficiently adhered to the fuel cell element prior to drying the coating in the channel. The method of claim 1, wherein the dispersant comprises an alcohol. 4. A process according to claim 3, wherein the alcohol is present in at least 30% by volume of the liquid phase. The method of claim 4, wherein the liquid phase further comprises 0.1-70% by volume of water of the liquid phase. The method according to claim 3, wherein the alcohol comprises at least one of methanol, ethanol, or propanol. The method of claim 1, wherein the nanoparticle dispersant comprises an organic solvent capable of forming a solution with water. 8. A method according to claim 7, wherein the liquid phase further comprises water. Applying the aqueous solution containing the polyelectrolyte polymer to the bipolar plate and bonding the polyelectrolyte polymer to the bipolar plate before the submerging step;
The method of claim 1, further comprising: The method of claim 18, wherein the polyelectrolyte polymer comprises a cationic functional group. The method of claim 18, wherein the polyelectrolyte polymer comprises an anionic functional group. The method of claim 18, further comprising applying a second coating material to the polyelectrolyte polymer adhered to the fuel cell element. The method of claim 19, wherein a second coating material containing a negative functional group is applied to the polyelectrolyte polymer adhered to the fuel cell element to form an ionic bond between the negative functional group and the positive functional group. . The method of claim 18, wherein the nanoparticles comprise negative functional groups. The method of claim 18, wherein the nanoparticles comprise siloxane. The method of claim 18, wherein the nanoparticles comprise silicon dioxide. (A) applying an aqueous polyelectrolyte polymer to a fuel cell bipolar plate having an upper surface including a plurality of lands and channels, and bonding the polyelectrolyte polymer to the bipolar plate;
(B) removing the polyelectrolyte polymer not adhered to the bipolar plate;
(C) applying a second coating material to the polyelectrolyte polymer adhered to the bipolar plate;
(D) removing the second coating material not adhered to the polyelectrolyte polymer adhered to the bipolar plate;
(E) submerging the fuel cell bipolar plate in a bath comprising nanoparticles and a liquid phase containing a nanoparticle dispersant;
(F) removing the fuel cell bipolar plate from the vessel and allowing the coating to dry so that the nanoparticle coating adheres to the fuel cell element;
(G) rinsing the fuel cell bipolar plate to remove nanoparticles that are not sufficiently adhered to the fuel cell element;
(H) removing the nanoparticle-containing coating from the bipolar plate land while leaving the nanoparticle-containing coating in the bipolar plate channel before the coating dries and solidifies while the coating is wet;
(I) drying the coating in the channel. 27. The method of claim 26, wherein removing the coating from the land comprises wiping the coating from the land. 28. The method of claim 27, wherein wiping comprises moving the blade across the land. 27. The method of claim 26, further comprising repeating (a)-(d) multiple times. 27. The method of claim 26, further comprising repeating (f)-(g) multiple times. (A) removing grease and contaminants from the bipolar plate by immersing the fuel cell bipolar plate in a pretreatment solution;
(B) rinsing the bipolar plate in the first tank of deionized water;
(C) rinsing the bipolar plate in a second tank of deionized water;
(D) immersing the bipolar plate in the first aqueous solution of the first polyelectrolyte polymer;
(E) rinsing the bipolar plate in a third bath of deionized water to remove the first polyelectrolyte polymer not adhered to the bipolar plate;
(F) rinsing the bipolar plate in the fourth tank of deionized water;
(G) a step of immersing the bipolar plate in a second dispersion containing the second coating material and containing nanoparticles and alcohol;
(H) rinsing the bipolar plate in a fourth tank of deionized water to remove the second coating material not adhered to the first polyelectrolyte polymer adhered to the bipolar plate;
(I) rinsing the bipolar plate in the fifth tank of deionized water;
(J) repeating (d) to (l) three times;
(K) removing the coating from the land while the coating from the rinse step is still wet;
(L) A method comprising a step of drying a bipolar plate.

Images